Coronary artery disease is the leading cause of mortality in developed countries. In the United States, a heart attack occurs approximately every 20 seconds. Aspirin inhibition of cyclooxygenase has been shown to be beneficial in patients presenting with acute coronary syndrome and acute myocardial infarction. Researchers found that the median platelet inhibition times for chewed baby aspirin 324 mg, soluble aspirin (alka-seltzer) 325 mg, and whole compressed non-enteric coated aspirin 324 mg, were 7.5 minutes, 7.5 minutes, and 10.0 minutes, respectively. Schwertner, et al, “Effects of different aspirin formulations on platelet aggregation times and on plasma salicylate concentration.” Thromb Res. 2006; 118(4): 529-34. Epub 2005 Nov. 18. Within 7.5 minutes, though, an individual could be dead from one of a number of potentially fatal arrhythmias such as ventricular tachycardia, ventricular fibrillation or complete heart block. Early administration of a novel intravenous aspirin formulation could start benefitting the patient in a matter of seconds, whereas the full benefit of traditional aspirin may not take effect until major sequelae, complications or death has occurred. In a person presenting with an acute myocardial infarction, intravenous aspirin is the preferred route for early platelet aggregation inhibition. According to the American Heart Association's 2007 National STEMI Statistics, 75% of the nation's acute care hospitals are not capable of performing life-saving PCI (Percutaneous Coronary Intervention) for STEMI (ST elevation myocardial infarction) patients. As such, there is a clear unmet need for a novel intravenous aspirin with improved pharmacokinetics and pharmacodynamics in patients presenting with acute myocardial infarction.
Aspirin inhibits prostanoid biosynthesis, in particular that of thromboxane A2 and prostaglandins PGE2 and PGI2. Aspirin irreversibly inhibits platelet cyclooxygenase 1 (COX-1) through acetylation of the amino acid serine at position 529, thereby preventing arachidonic acid access to the COX-1 catalytic site through steric hindrance. By inhibiting COX-1, the platelet is unable to synthesize prostaglandin H2, which would otherwise be converted to thromboxane A2, which causes platelet aggregation, an early step in the coagulation cascade.
Control of the inflammatory process is regulated by a cascade of biomolecular mechanisms. These mechanisms occur via two pathways: the cyclooxygenase pathway, which results in the formation of prostaglandins, and the lipoxygenase pathway, which results in the formation of leukotrienes. Non-steroid anti-inflammatory drugs (NSAID), like aspirin, function via the cyclooxygenase pathway. There are three major human lipoxygenases. They differ in the position of the double bond on the arachidonic acid molecule. These human lipoxygenases include the 5-, 12-, and 15-lipoxygenases, which respectively catalyze the insertion of oxygen at the C-5, C-12 and C-15 positions of arachidonic acid. The resulting leukotrienes and lipoxins provide signaling molecules associated with a variety of human diseases such as asthma, atherosclerosis, psoriasis and inflammatory bowel disease. Leukotrienes and lipoxins, have been implicated as critical signaling molecules in a variety of cancers. 15-HLO has been shown to be a key biological agent in colorectal cancers, while 12-HLO is involved in pancreatic, breast and prostate cancers. 5-HLO is up-regulated in prostate cancer and its inhibition abolishes all cell proliferation, inducing apoptosis.
Tylenol accounts for most drug overdoses in the United States and other Western countries. The hepatotoxicity of Tylenol (acetaminophen), statins (cholesterol lowering drugs), antiretrovirals (taken for HIV and AIDS), and alcohol are well known. Researchers at Yale University have now provided new insight into the mechanism by which acetaminophen causes liver damage in mice and determined that aspirin provides substantial protection from these toxic effects of acetaminophen. Wajahat Z Mehal; Acetaminophen-induced hepatotoxicity in mice is dependent on Tlr9 and the Nalp3 Inflammasome; Journal of Clinical Investigation; Jan. 26, 2009.
Currently, intravenous aspirin is not approved for use in the United States. The poor solubility of aspirin in water and its rapid hydrolysis in the plasma to salicylic acid and acetic acid have limited its intravenous use.
Attempts have been made in the past to produce an aspirin product having an acceptable solubility, but none have proven to be totally satisfactory.
For example, the introduction of Bayer aspirin, as well as Disprin (distributed in the United Kingdom), into water results in the formation of a cloudy suspension indicative of incomplete dissolution in water. Aspro Clear (distributed in Australia and New Zealand and marketed throughout Europe) imparts a non-cloudy, snow globe effect in water for more than three minutes after the tablets have effervesced.
It is well-known that lysine acetylsalicylate (sold as, e.g., Aspegic and Aspisol) is suitable for intravenous administration. The suitability of lysine for intravenous administration is due to the formation of a salt of acetylsalicylic acid with a basic amino acid, with the salt form exhibiting improved solubility. Lysine acetylsalicylate, however, is not approved by the FDA for use in the United States. See e.g., FDA Reports 2006-2008: Aspegic Side-Effect Report #5076936-8 (after drug was administered, patient developed cardio-respiratory arrest and ventricular fibrillation and died); FDA Reports 2006-2008: Aspegic Side Effect Report #5379074-X (after drug was administered, patient experienced angina pectoris and recovered).
U.S. Pat. Nos. 5,665,388 and 5,723,453 to Phykitt, disclose an essentially sodium-free, soluble alkaline aspirin compound. The formulations disclosed in these references, however, suffer from a number of disadvantages. One disadvantage is that the use of bicarbonates, as disclosed therein, causes gas to be formed when ingested by patients. Another disadvantage is that the relatively high pH of the compositions disclosed therein (i.e., greater than 8.0) leads to rapid hydrolysis and instability of the drug substance and, therefore, a shortened shelf-life.
Many of the formulations disclosed in U.S. Pat. Nos. 5,157,030 and 5,776,431 to Galat are formed as two separate compositions (mixture “A” and mixture “B”), which is disadvantageous from manufacturing, packaging and use standpoints. Furthermore, the formulations in these references are blended and then directly added to water. There is no indication that the blended product is stable. Further, compositions formulated in accordance with the Galat patents take up to two to three minutes to substantially completely dissolve in water.
Compositions formulated in accordance with the methods disclosed in Patent Application Publication No. 2006/0292225 to Felix take up to 15-30 seconds to completely dissolve in water with stirring.
Theanine, like aspirin, is known to have salutary effects. It is found in ordinary tea leaves from Camellia sinensis and the mushroom Xerocomus badius, but is otherwise rare in nature. Preliminary research, suggests that L-theanine promotes alpha wave generation in the brain. Thereby, an awake, alert and relaxed physical and mental condition is achieved, which demonstrates theanine's effectiveness in stress management. L-theanine does not cause drowsiness or impair a person's motor skills. It has been shown to work antagonistically against the negative side effects of caffeine, to increase dopamine and serotonin concentrations in the brain, to be effective in reducing the hypertension and disturbance of sleep often associated with the use of caffeine, and to diminish symptoms of premenstrual syndrome. Laboratory studies indicate that theanine produces these effects by increasing the level of GABA (gamma-aminobutyric acid), an important inhibitory neurotransmitter in the brain.
It has been reported that theanine supports the immune system and may reduce plasma total cholesterol, cholesterol ester and very-low-density lipoprotein cholesterol.
Studies on the effects of theanine on alcohol metabolism and hepatic toxicity have shown that theanine is effective against alcoholic liver injury.
Theanine also has the potential to protect neurons from excesses of glutamate. Glutamate is an essential brain chemical that may be released in excess amounts with some disease conditions (e.g., amyotrophic lateral sclerosis and cerebrovascular dementia) and with brain injuries, as occurs with strokes or physical injuries. Theanine may protect against this damage by blocking glutamine entrance to cells due to the similarity in the stereochemical structures of theanine and glutamine.
A direct metabolite of amino acids glutamine and glutamic acid, theanine is made different by its ethyl-N alkylation of glutamine's nitrogen. The amino acid scaffolds glutamine and its metabolite glutamic acid provide the general, alpha amino acid core structure responsible for theanine's transport, while ethyl-N alkylation of glutamine provides both its transport and pharmacological properties. The similarity of glutamine's and glutamic acid's structure with theanine allows theanine to be substrate and product competitors for all physiological glutamine and glutamic acid reactions, providing their charges are similar. Therefore, wherever glutamine or glutamic acid is a metabolite, theanine can activate, inhibit or add to target activity. This is why its effects are so far-reaching. It is a glutamine mimetic with pharmacological activity. Glutamine is a significant consumer of ATP for nitrogen incorporation, which may explain some of the anti-cancer and anti-HIV activity of theanine. If N-fixation is inhibited, cell or viral structure growth is also inhibited.
The amino acids glutamine and glutamic acid have common molecular elements with theanine. Some examples of common molecular elements are pl(isoelectric point), polarity, hydropathy index, and elements that support their role as metabolite targets for theanine. The overlapping molecular properties allow theanine to function as a glutamine or glutamic acid analogue. These properties relate to the electrostatic profile of theanine under physiological conditions and its overall structural geometry, which includes atoms common to the related core amino acids glutamine and glutamic acid. The coincident array of atoms and the relative electrostatic structure of glutamine and glutamic acid allow them to serve as targets for theanine. The targets also include the enzymes, proteins, receptors or other macromolecules they effectively bind. In the case of glutamic acid, the atoms that make up the isosteric structure up to the C5 or gamma carboxyl are in the same array as theanine. In the case of glutamine, the isosteric and isoelectronic atoms of glutamine are equal to theanine's where hydrogen has been replaced by ethyl (—C2H5) on the carboxamide nitrogen of glutamine.
Glutathione is the liver's first-line defense against drugs and chemicals. It is used by cancer cells against drugs and chemicals. Cancer cells use glutathione to detoxify doxorubicin and escort the drug out of cells. Theanine is able to interfere with this process due to its structural similarity to glutamate. Glutamic acid, or glutamate, is one of the components of glutathione, the drug detoxifier. Because it looks like glutamic acid, cancer cells take up and mistakenly use the theanine to create glutathione. But the glutathione they create with theanine does not detoxify like natural glutathione. Instead, this theanine-based glutathione appears to block the ability of cancer cells to detoxify.
Further, in addition to enhancing doxorubicin's cancer-killing effects without harming healthy tissue, theanine also keeps doxorubicin out of healthy tissue. This is a major added benefit, since one of the drawbacks of the use of doxorubicin is its toxicity to the heart. The potential of theanine as an adjunct to cancer chemotherapy was proposed by researcher Yasuyuki Sadzuka, who confirmed that theanine, a major amino acid in green tea, enhances the antitumor activity of doxorubicin (DOX) without an increase in DOX-induced side effects. He postulated that the action of theanine is due to decreases in glutamate uptake via inhibition of the glutamate transporter and reduction of glutathione and DOX export from the cell. Theanine enhances the antitumor activity not only of DOX but also of cisplatin and irinotecan (CPT-11). In essence, Sadzuka found that theanine could block the export of doxorubicin (Adriamycin) from cancer cells by blocking the glutamate and glutathione transporter mechanisms; the elevated level of the drug within cancer cells strongly inhibits the tumor. Sadzuka Y, et al., “The effects of theanine, as a novel biochemical modulator, on the antitumor activity of adriamycin,” Cancer Letters 1996; 105(2): 203-209; Sadzuka Y, et al., “Modulation of cancer chemotherapy by green tea,” Clinical Cancer Research 1998; 4(1): 153-156; Sadzuka Y, et al., “Efficacies of tea components on doxorubicin induced antitumor activity and reversal of multidrug resistance,” Toxicology Letters 2000; 114 (1-3): 155-162; Sadzuka Y, et al., “Improvement of idarubicin induced antitumor activity and bone marrow suppression by theanine, a component of tea,” Cancer Letters 2000; 158(2): 119-24; Sadzuka Y, et al., “Enhancement of the activity of doxorubicin by inhibition of glutamate transporter,” Toxicology Letters 2001; 123(2-3):159-67; Sadzuka Y, et al., “Effect of dihydrokainate on the antitumor activity of doxorubicin,” Cancer Letters 2002; 179(2): 157-163.
Therapeutic compounds, such as aspirin, are most stable in a crystalline form, but can display poor aqueous solubilities and slow dissolution rates. These properties impart the tendency to reduce the bioavailability of the active pharmaceutical ingredient (API), thereby slowing absorption.
A cocrystal is a multiple-component crystal, in which two or more molecules associate (but do not bond) on the molecular level in solid crystalline form under ambient conditions. They are attractive to the pharmaceutical industry because they offer opportunities to modify the chemical and/or physical properties of an API without the need to make or break covalent bonds. In pharmaceutical cocrystals, the molecular structure of the API is not changed. This has important implications for streamlined regulatory approval of new forms. By their very nature, APIs, molecules that contain exterior hydrogen-bonding moieties, are predisposed to formation of cocrystals. Pharmaceutical cocrystals will afford forms of APIs with improved physical properties such as solubility, stability, hygroscopicity, and dissolution rate. Physical properties are not just dependent upon molecular structure. They are also critically dependent upon supramolecular chemistry and its influence upon crystal structure. The application of the concepts of supramolecular synthesis and crystal engineering to the development of pharmaceutical cocrystals offers many opportunities related to drug development and delivery.
Thus, a water-soluble aspirin-theanine cocrystal composition which has enhanced stability and bioactivity as compared to previously-known, water-soluble analgesic compositions, and which delivers the salutary effects of both aspirin and theanine, is needed.
The present invention satisfies these and other medical needs and overcomes deficiencies found in the prior art.